Wafer dicing from wafer backside

ABSTRACT

Methods of dicing semiconductor wafers, each wafer having a plurality of integrated circuits, are described. For example, a method includes applying a protection tape to a wafer front side, the wafer having a dicing tape attached to the wafer backside. The dicing tape is removed from the wafer backside to expose a die attach film disposed between the wafer backside and the dicing tape. Alternatively, if no die attach film is initially disposed between the wafer backside and the dicing tape, a die attach film is applied to the wafer backside at this operation. A water soluble mask is applied to the wafer backside. Laser scribing is performed on the wafer backside to cut through the mask, the die attach film and the wafer, including all layers included within the front side and backside of the wafer. A plasma etch is performed to treat or clean surfaces of the wafer exposed by the laser scribing. A wafer backside cleaning is performed and a second dicing tape is applied to the wafer backside. The protection tape is the removed from the wafer front side.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/740,301, filed on Dec. 20, 2012, the entire contents of which arehereby incorporated by reference herein.

BACKGROUND

1) Field

Embodiments of the present invention pertain to the field ofsemiconductor processing and, in particular, to methods of dicingsemiconductor wafers, each wafer having a plurality of integratedcircuits thereon.

2) Description of Related Art

In semiconductor wafer processing, integrated circuits are formed on awafer (also referred to as a substrate) composed of silicon or othersemiconductor material. In general, layers of various materials whichare either semiconducting, conducting or insulating are utilized to formthe integrated circuits. These materials are doped, deposited and etchedusing various well-known processes to form integrated circuits. Eachwafer is processed to form a large number of individual regionscontaining integrated circuits known as dice.

Following the integrated circuit formation process, the wafer is “diced”to separate the individual die from one another for packaging or for usein an unpackaged form within larger circuits. The two main techniquesthat are used for wafer dicing are scribing and sawing. With scribing, adiamond tipped scribe is moved across the wafer surface along pre-formedscribe lines. These scribe lines extend along the spaces between thedice. These spaces are commonly referred to as “streets.” The diamondscribe forms shallow scratches in the wafer surface along the streets.Upon the application of pressure, such as with a roller, the waferseparates along the scribe lines. The breaks in the wafer follow thecrystal lattice structure of the wafer substrate. Scribing can be usedfor wafers that are about 10 mils (thousandths of an inch) or less inthickness. For thicker wafers, sawing is presently the preferred methodfor dicing.

With sawing, a diamond tipped saw rotating at high revolutions perminute contacts the wafer surface and saws the wafer along the streets.The wafer is mounted on a supporting member such as an adhesive filmstretched across a film frame and the saw is repeatedly applied to boththe vertical and horizontal streets. One problem with either scribing orsawing is that chips and gouges can form along the severed edges of thedice. In addition, cracks can form and propagate from the edges of thedice into the substrate and render the integrated circuit inoperative.Chipping and cracking are particularly a problem with scribing becauseonly one side of a square or rectangular die can be scribed in the <110>direction of the crystalline structure. Consequently, cleaving of theother side of the die results in a jagged separation line. Because ofchipping and cracking, additional spacing is required between the diceon the wafer to prevent damage to the integrated circuits, e.g., thechips and cracks are maintained at a distance from the actual integratedcircuits. As a result of the spacing requirements, not as many dice canbe formed on a standard sized wafer and wafer real estate that couldotherwise be used for circuitry is wasted. The use of a saw exacerbatesthe waste of real estate on a semiconductor wafer. The blade of the sawis approximate 15 microns thick. As such, to insure that cracking andother damage surrounding the cut made by the saw does not harm theintegrated circuits, three to five hundred microns often must separatethe circuitry of each of the dice. Furthermore, after cutting, each dierequires substantial cleaning to remove particles and other contaminantsthat result from the sawing process.

Plasma dicing has also been used, but may have limitations as well. Forexample, one limitation hampering implementation of plasma dicing may becost. A standard lithography operation for patterning resist may renderimplementation cost prohibitive. Another limitation possibly hamperingimplementation of plasma dicing is that plasma processing of commonlyencountered metals (e.g., copper) in dicing along streets can createproduction issues or throughput limits.

SUMMARY

Embodiments of the present invention include methods of dicingsemiconductor wafers, each wafer having a plurality of integratedcircuits thereon.

In an embodiment, a method of dicing a semiconductor wafer having aplurality of integrated circuits includes applying a protection tape toa wafer front side, the wafer having a dicing tape attached to the waferbackside. The dicing tape is removed from the wafer backside to expose adie attach film disposed between the wafer backside and the dicing tape.A water soluble mask is applied to the wafer backside. Laser scribing isperformed on the wafer backside to cut through the mask, the die attachfilm and the wafer, including all layers included on the front side andbackside of the wafer. A plasma etch is performed to treat or cleansurfaces of the wafer exposed by the laser scribing. A wafer backsidecleaning is performed and a second dicing tape is applied to the waferbackside. The protection tape is the removed from the wafer front side.

In another embodiment, a method of dicing a semiconductor wafer having aplurality of integrated circuits includes applying a protection tape toa wafer front side, the wafer having a dicing tape attached to the waferbackside. The dicing tape is removed from the wafer backside. A dieattach film is then applied to the wafer backside. A water soluble maskis then applied to the wafer backside. Laser scribing is performed onthe wafer backside to cut through the the mask, die attach film and thewafer, including all layers included on the front side and backside ofthe wafer. A plasma etch is performed to treat or clean surfaces of thewafer exposed by the laser scribe. A wafer backside cleaning isperformed and a second dicing tape is applied to the wafer backside. Theprotection tape is the removed from the wafer front side.

In another embodiment, a method is provided for dicing a semiconductorwafer having a plurality of integrated circuits covered by a protectiontape on a front side thereof and having metallization on a backsidethereof. The method involves exposing a die attach film disposed on thesemiconductor wafer backside. The method also involves applying a maskto the exposed die attach film on the semiconductor wafer backside. Themethod also involves laser scribing from the semiconductor waferbackside to cut through the mask, the die attach film, the metallizationon the backside of the semiconductor wafer, the semiconductor wafer, andthe integrated circuits on the front side of the semiconductor wafer.The method also involves plasma etching to treat or clean surfaces ofthe semiconductor wafer exposed by the laser scribing. The method alsoinvolves applying a dicing tape to the laser scribed semiconductor waferbackside.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart including operations for a backside laser plusplasma etch dicing process, in accordance with an embodiment of thepresent invention.

FIGS. 2A and 2B illustrate cross-sectional views representing variousoperations in a backside laser plus plasma etch dicing process, inaccordance with an embodiment of the present invention.

FIG. 3 illustrates the effects of using a laser pulse in the femtosecondrange versus longer pulse times, in accordance with an embodiment of thepresent invention.

FIG. 4 illustrates compaction on a semiconductor wafer achieved by usingnarrower streets versus conventional dicing which may be limited to aminimum width, in accordance with an embodiment of the presentinvention.

FIG. 5 illustrates freeform integrated circuit arrangement allowingdenser packing and, hence, more die per wafer versus grid alignmentapproaches, in accordance with an embodiment of the present invention.

FIG. 6 illustrates a block diagram of a tool layout for laser and plasmadicing of wafers or substrates, in accordance with an embodiment of thepresent invention.

FIG. 7 illustrates a block diagram of an exemplary computer system, inaccordance with an embodiment of the present invention.

DETAILED DESCRIPTION

Methods of dicing semiconductor wafers, each wafer having a plurality ofintegrated circuits thereon, are described. In the followingdescription, numerous specific details are set forth, such asfemtosecond-based laser scribing and plasma etching conditions andmaterial regimes, in order to provide a thorough understanding ofembodiments of the present invention. It will be apparent to one skilledin the art that embodiments of the present invention may be practicedwithout these specific details. In other instances, well-known aspects,such as integrated circuit fabrication, are not described in detail inorder to not unnecessarily obscure embodiments of the present invention.Furthermore, it is to be understood that the various embodiments shownin the Figures are illustrative representations and are not necessarilydrawn to scale.

A hybrid wafer or substrate dicing process involving an initial laserscribe and subsequent plasma treatment may be implemented for diesingulation. The laser scribe process may be used to cleanly remove amask layer, organic and inorganic dielectric layers, and device layerson both sides of a wafer, as well as cut through an interveningsubstrate. The plasma etch or treatment portion of the dicing processmay then be employed to yield clean die or chip singulation or dicing.

More specifically, one or more embodiments are directed to wafer orsubstrate dicing from the wafer or substrate backside. Particularembodiments include one of more of wafer dicing, backside dicing,backside metal/dielectric structures, picosecond-UV laser scribing,infrared femtosecond laser scribing, full thickness laser cutting, andthe use of a water soluble mask. Approaches described herein may haveimplications for general laser scribing plus plasma etch hybridprocesses used to singulate integrated circuit (IC) chips or dies fromwafers or substrates. Other potential applications include MEMS waferdicing. Approaches herein may be in contrast to femtosecond laserscribing plus plasma etch hybrid processing that involve use of afemtosecond laser to cleanly remove a mask layer, organic and inorganicdielectric layers and device layers, followed by plasma etch through asilicon layer (e.g., wafer or substrate) to realize chip singulation ordicing. Instead one or more embodiments involve continued scribing bythe laser process through the wafer or substrate (e.g., from thebackside), followed by a touch up or cleaning silicon etch process.

More generally, some wafers or substrates bear metal and/or dielectriclayers on the wafer or substrate backside. Additionally, a die attachfilm is often added on wafer backside and is subjected to the dicingprocess along with the wafer or substrate, e.g., the die attach film iscut or patterned in the dicing process. In a conventional laser plusetch dicing process, an additional laser scribing operation is otherwiseneeded post plasma etch to remove such backside non-silicon layers. Theadditional laser operation may involve time consuming realignment ofwafers. Furthermore, laser scribing and plasma etching from the wafer orsubstrate front side can demand use of a thick mask layer on the waferor substrate front side to sufficiently protect metal bumps and pillars.There is also the potential to oxidize bumps and contaminate a deviceside of the wafer or substrate since the front side is exposed to, or atleast facing the plasma during etching. As such, if additional backsidenon-silicon layers become a significant portion of the structurerequiring singulation, dicing from front side may cause throughput andquality issues.

Accordingly, as described in greater detail below, one or moreembodiments involve dicing from a wafer or substrate backside. As anexample, FIG. 1 is a flowchart 100 including operations for a backsidelaser plus plasma etch dicing process, in accordance with an embodimentof the present invention. Referring to flowchart 100, at operation 102,a protection tape is applied to a wafer front side, the wafer having adicing tape attached to the wafer backside. At operation 104, the dicingtape is removed from the wafer backside to expose a die attach filmdisposed between the wafer backside and the dicing tape. Alternatively,if no die attach film is initially disposed between the wafer backsideand the dicing tape, a die attach film is applied to the wafer backsideat this operation. At operation 106, a water soluble mask is applied tothe wafer backside, e.g., on the die attach film. At operation 108, alaser scribe is performed on the wafer backside to cut through the dieattach film and the wafer, including all layers on the front side andbackside of the wafer (such as backside and font side metal ordielectric layers and/or device layers). At operation 110, a plasma etchis performed to treat or clean surfaces of the wafer exposed by thelaser scribe (e.g., silicon sidewalls exposed by the laser scribe). Theetch process may be used to clean debris and/or enhance die strength. Atoperation 112, a wafer backside cleaning is performed and a seconddicing tape is applied to the wafer backside. At operation 114, theprotection tape is removed from the wafer front side.

As a structural example, FIGS. 2A and 2B illustrate cross-sectionalviews representing various operations in a backside laser plus plasmaetch dicing process, in accordance with an embodiment of the presentinvention.

Referring to FIG. 2A, structure 202 includes a silicon substrate havingdevice layers disposed on the front side of the substrate and metaland/or dielectric layers disposed on the backside of the substrate. Atoperation 203, as depicted by the resulting structure 204, a protectiontape is mounted on the wafer front side, e.g., on the device layers. Thesubstrate is mounted on a frame via the protection tape. Also, a dieattach film and a dicing tape are disposed on the backside of thesubstrate, e.g., on the metal and/or dielectric layers disposed on thebackside of the substrate. At operation 205, as depicted by theresulting structure 208, a water soluble mask is disposed on the dieattach film of the backside of the substrate. At operation 207, as isalso depicted by the resulting structure 208, from the backside of thesubstrate, a laser scribing process is performed through the watersoluble mask, the die attach film, the metal and/or dielectric layers,the silicon substrate, and the device layers. The laser scribing processstops on or into the protection tape on the front side of the substrate.Additionally, at operation 207, a plasma etch process is used to cleanexposed sidewalls of the silicon substrate. Additionally, the plasmaetch process can be used to remove a certain amount of the silicon fromthe sidewalls for die strength enhancement. At operation 209, the watersoluble mask is removed, e.g., by an aqueous based cleaning process, toprovide structure 210. Then, referring to FIG. 2B, at operation 211, asdepicted by the resulting structure 212, a dicing tape is applied to thebackside of the substrate, e.g., on the scribed die attach film. Then,the protection tape (and corresponding frame) is removed from the dicedsubstrate front side. The result is a plurality of chips or diessingulated from the silicon substrate. The dies or chips are held inplace by the dicing tape for transport, e.g., on a second frame.

Embodiments described herein can include one or more of the followingadvantages of dicing from the backside of a wafer or substrate: (1)since bumps are not involved in the backside metallization, maskthickness (e.g., water soluble mask thickness) can be much thinner thanotherwise required for a front side process. As such, less time isneeded for opening the mask, compensating for any additional timerequired for cutting through the whole wafer with a laser scribingprocess. Also, a cost savings can be realized by using less maskmaterial. Furthermore, time duration for mask coating and baking can bereduced, e.g., as compared to a thick mask coating process wheremultiple layer coatings may be involved. Use of a thin mask coating canalso translate to improved coating quality versus a thick mask which canhave air bubbles trapped therein causing etch defects in the wafer. (2)Use of a plasma etch to repair the diced sidewalls involvessignificantly less silicon etch away, and significantly reduced etchtime. (3) Dicing from backside will not substantially impact throughputsince the process is a laser cut plus plasma versus a scribe front side,then etch, then scribe backside process. (4) A significant reduction inopportunities for bump oxidization and device side contamination may berealized since the front side is untouched and can be placed on acooling chuck. (5) Specification for laser performance may be relaxedsuch that longer wavelength and/or longer pulsewidth lasers may be used.This can reduce laser cost by widening laser source options. Potentialsuitable laser sources include picosecond-UV lasers, infraredfemtosecond-lasers (e.g., instead of SHG (˜500 nm)-femtosecond lasers,which are the preferred laser sources for front side dicing). Moreflexibility may be realized since backside laser cutting involves laserfirst removal of silicon which has good absorption to photons at widewavelength/pulse width before it touches device layers.

Thus, in accordance with an embodiment of the present invention, acombination of backside picosecond- or femtosecond-based laser scribingand plasma etching is used to dice a semiconductor wafer intoindividualized or singulated integrated circuits. In one embodiment,backside picosecond- or femtosecond-based laser scribing is used as anessentially, if not totally, non-thermal process. For example, thebackside picosecond- or femtosecond-based laser scribing may belocalized with no or negligible heat damage zone. In an embodiment,approaches herein are used to singulated integrated circuits havingultra-low k films, and wafers having metallization on both the front andback surfaces. With convention dicing, saws may need to be slowed downto accommodate such low k films.

In accordance with an embodiment of the present invention, a watersoluble mask is used in a backside laser scribing and etch process. Inan embodiment, the water soluble mask is a film that is readilydissolvable in an aqueous media. For example, in one embodiment, thewater soluble mask is composed of a material that is soluble in one ormore of an alkaline solution, an acidic solution, or in deionized water.In one embodiment, the water soluble mask has a thickness approximatelyin the range of 5-60 microns. In a specific embodiment, the watersoluble mask has a thickness of approximately 20 microns. In anembodiment, the water soluble mask maintains its water solubility upon aheating process, such as heating approximately in the range of 50-160degrees Celsius. For example, in one embodiment, the water soluble maskis soluble in aqueous solutions following exposure to chamber conditionsused in a laser and plasma etch singulation process. In one embodiment,the water soluble mask is composed of a material such as, but notlimited to, polyvinyl alcohol, polyacrylic acid, dextran,polymethacrylic acid, polyethylene imine, or polyethylene oxide. In aspecific embodiment, the water soluble mask has an etch rate in anaqueous solution approximately in the range of 1-15 microns per minuteand, more particularly, approximately 1.3 microns per minute. In anotherspecific embodiment, the water soluble mask is formed by a spin-ontechnique.

In an embodiment, the semiconductor wafer or substrate that is scribedis composed of a material suitable to withstand a fabrication processand upon which semiconductor processing layers may suitably be disposed.For example, in one embodiment, the semiconductor wafer or substrate iscomposed of a group IV-based material such as, but not limited to,crystalline silicon, germanium or silicon/germanium. In a specificembodiment, providing the semiconductor wafer includes providing amonocrystalline silicon substrate. In a particular embodiment, themonocrystalline silicon substrate is doped with impurity atoms. Inanother embodiment, the semiconductor wafer or substrate is composed ofa III-V material such as, e.g., a III-V material substrate used in thefabrication of light emitting diodes (LEDs).

In an embodiment, the semiconductor wafer or substrate has disposed onits front side an array of semiconductor devices. Examples of suchsemiconductor devices include, but are not limited to, memory devices orcomplimentary metal-oxide-semiconductor (CMOS) transistors fabricated ina silicon substrate and encased in a dielectric layer. A plurality ofmetal interconnects may be formed above the devices or transistors, andin surrounding dielectric layers, and may be used to electrically couplethe devices or transistors to form the integrated circuits. One or moreof the dielectric layers can be a low-k dielectric layer. In oneembodiment, the semiconductor wafer or substrate has disposedmetallization layers (and corresponding dielectric layers) on thebackside of the wafer or substrate. More generally, many functionallayers of different material types (e.g., conductors, insulators,semiconductors) and thicknesses can be disposed on both the backside andthe front side of the substrate. Such materials may include, but are notlimited to, organic materials such as polymers, metals, or inorganicdielectrics such as silicon dioxide and silicon nitride. A low Kdielectric layer may also be included (e.g., a layer having a dielectricconstant of less than the dielectric constant of 4.0 for silicondioxide). In a specific embodiment, the low K dielectric layers arecomposed of a carbon-doped silicon oxide material.

In an embodiment, the laser scribing process includes using a laserhaving a pulse width in the femtosecond range. Specifically, a laserwith a wavelength in the visible spectrum plus the ultra-violet (UV) andinfra-red (IR) ranges (totaling a broadband optical spectrum) may beused to provide a femtosecond-based laser, i.e., a laser with a pulsewidth on the order of the femtosecond (10⁻¹⁵ seconds). In oneembodiment, ablation is not, or is essentially not, wavelength dependentand is thus suitable for complex films such as low-k dielectric layersand backside metallization layers.

FIG. 3 illustrates the effects of using a laser pulse in the femtosecondrange versus longer frequencies, in accordance with an embodiment of thepresent invention. Referring to FIG. 3, by using a laser with a pulsewidth in the femtosecond range heat damage issues are mitigated oreliminated (e.g., minimal to no damage 302C with femtosecond processingof a via 300C) versus longer pulse widths (e.g., damage 302B withpicosecond processing of a via 300B and significant damage 302A withnanosecond processing of a via 300A). The elimination or mitigation ofdamage during formation of via 300C may be due to a lack of low energyrecoupling (as is seen for picosecond-based laser ablation) or thermalequilibrium (as is seen for nanosecond-based laser ablation), asdepicted in FIG. 3. However, as mentioned above, picosecond- orfemtosecond-based may be used for embodiments herein since parametersmay be relaxed during a backside laser scribing process, as opposed to afront side laser scribing process.

As mentioned above, in an embodiment, etching the semiconductor wafer orsubstrate includes using a plasma etching process. In one embodiment, anultra-high-density plasma source is used for the plasma etching portionof the die singulation process. An example of a process chamber suitableto perform such a plasma etch process is the Applied Centura® Silvia™Etch system available from Applied Materials of Sunnyvale, Calif., USA.The Applied Centura® Silvia™ Etch system combines the capacitive andinductive RF coupling, which gives much more independent control of theion density and ion energy than was possible with the capacitivecoupling only, even with the improvements provided by magneticenhancement. This combination enables effective decoupling of the iondensity from ion energy, so as to achieve relatively high densityplasmas without the high, potentially damaging, DC bias levels, even atvery low pressures. This results in an exceptionally wide processwindow. However, any plasma etch chamber capable of treating and/oretching silicon may be used. In a specific embodiment, the etch processis based on a plasma generated from a reactive gas, which generally afluorine-based gas such as SF₆, C₄ F₈, CHF₃, XeF₂, or any other reactantgas capable of etching silicon at a relatively fast etch rate.

In another embodiment, a plurality of integrated circuits may beseparated by streets having a width of approximately 10 microns orsmaller. The use of a backside picosecond- or femtosecond-based laserscribing approach, at least in part due to the tight profile control ofthe laser, may enable such compaction in a layout of integratedcircuits. For example, FIG. 4 illustrates compaction on a semiconductorwafer or substrate achieved by using narrower streets versusconventional dicing which may be limited to a minimum width, inaccordance with an embodiment of the present invention.

Referring to FIG. 4, compaction on a semiconductor wafer is achieved byusing narrower streets (e.g., widths of approximately 10 microns orsmaller in layout 402) versus conventional dicing which may be limitedto a minimum width (e.g., widths of approximately 70 microns or largerin layout 400). It is to be understood, however, that it may not alwaysbe desirable to reduce the street width to less than 10 microns even ifotherwise enabled by a femtosecond-based laser scribing process. Forexample, some applications may require a street width of at least 40microns in order to fabricate dummy or test devices in the streetsseparating the integrated circuits.

In another embodiment, a plurality of integrated circuits may bearranged on a semiconductor wafer or substrate in a non-restrictedlayout. For example, FIG. 5 illustrates freeform integrated circuitarrangement allowing denser packing. The denser packing may provide formore die per wafer versus grid alignment approaches, in accordance withan embodiment of the present invention. Referring to FIG. 5, a freeformlayout (e.g., a non-restricted layout on semiconductor wafer orsubstrate 502) allows denser packing and hence more die per wafer versusgrid alignment approaches (e.g., a restricted layout on semiconductorwafer or substrate 500). In an embodiment, the speed of the laserablation and plasma etch singulation process is independent of die size,layout or the number of streets.

A single process tool may be configured to perform many or all of theoperations in a backside picosecond- or femtosecond-based laser ablationand plasma etch singulation process. For example, FIG. 6 illustrates ablock diagram of a tool layout for laser and plasma dicing of wafers orsubstrates, in accordance with an embodiment of the present invention.

Referring to FIG. 6, a process tool 600 includes a factory interface 602(FI) having a plurality of load locks 604 coupled therewith. A clustertool 606 is coupled with the factory interface 602. The cluster tool 606includes one or more plasma etch chambers, such as plasma etch chamber608. A laser scribe apparatus 610 is also coupled to the factoryinterface 602. The overall footprint of the process tool 600 may be, inone embodiment, approximately 3500 millimeters (3.5 meters) byapproximately 3800 millimeters (3.8 meters), as depicted in FIG. 6.

In an embodiment, the laser scribe apparatus 610 houses a picosecond- orfemtosecond-based laser. The picosecond- or femtosecond-based laser issuitable for performing a backside laser ablation portion of a laser andetch singulation process, such as the laser abalation processesdescribed above. In one embodiment, a moveable stage is also included inlaser scribe apparatus 600, the moveable stage configured for moving awafer or substrate (or a carrier thereof) relative to the picosecond- orfemtosecond-based laser. In a specific embodiment, picosecond- orfemtosecond-based laser is also moveable. The overall footprint of thelaser scribe apparatus 610 may be, in one embodiment, approximately 2240millimeters by approximately 1270 millimeters, as depicted in FIG. 6.

In an embodiment, the one or more plasma etch chambers 608 is an AppliedCentura® Silvia™ Etch system, available from Applied Materials ofSunnyvale, Calif., USA. The etch chamber may be specifically designedfor a silicon etch or treatment used in a process to create singulateintegrated circuits housed on or in single crystalline siliconsubstrates or wafers. In an embodiment, a high-density plasma source isincluded in the plasma etch chamber 608 to facilitate high silicon etchrates. In an embodiment, more than one etch chamber is included in thecluster tool 606 portion of process tool 600 to enable highmanufacturing throughput of the singulation or dicing process.

The factory interface 602 may be a suitable atmospheric port tointerface between an outside manufacturing facility with laser scribeapparatus 610 and cluster tool 606. The factory interface 602 mayinclude robots with arms or blades for transferring wafers (or carriersthereof) from storage units (such as front opening unified pods) intoeither cluster tool 606 or laser scribe apparatus 610, or both.

Cluster tool 606 may include other chambers suitable for performingfunctions in a method of singulation. For example, in one embodiment, inplace of an additional etch chamber, a deposition chamber 612 isincluded. The deposition chamber 612 may be configured for maskdeposition on or above a backside of a wafer or substrate prior to laserscribing of the wafer or substrate. In one such embodiment, thedeposition chamber 612 is suitable for depositing a water soluble masklayer. In another embodiment, in place of an additional etch chamber, awet/dry station 614 is included. The wet/dry station may be suitable forcleaning residues and fragments, or for removing a water soluble mask,subsequent to a laser scribe and plasma etch singulation process of asubstrate or wafer. In an embodiment, a metrology station is alsoincluded as a component of process tool 600.

Embodiments of the present invention may be provided as a computerprogram product, or software, that may include a machine-readable mediumhaving stored thereon instructions, which may be used to program acomputer system (or other electronic devices) to perform a processaccording to embodiments of the present invention. In one embodiment,the computer system is coupled with process tool 600 described inassociation with FIG. 6. A machine-readable medium includes anymechanism for storing or transmitting information in a form readable bya machine (e.g., a computer). For example, a machine-readable (e.g.,computer-readable) medium includes a machine (e.g., a computer) readablestorage medium (e.g., read only memory (“ROM”), random access memory(“RAM”), magnetic disk storage media, optical storage media, flashmemory devices, etc.), a machine (e.g., computer) readable transmissionmedium (electrical, optical, acoustical or other form of propagatedsignals (e.g., infrared signals, digital signals, etc.)), etc.

FIG. 7 illustrates a diagrammatic representation of a machine in theexemplary form of a computer system 700 within which a set ofinstructions, for causing the machine to perform any one or more of themethodologies described herein, may be executed. In alternativeembodiments, the machine may be connected (e.g., networked) to othermachines in a Local Area Network (LAN), an intranet, an extranet, or theInternet. The machine may operate in the capacity of a server or aclient machine in a client-server network environment, or as a peermachine in a peer-to-peer (or distributed) network environment. Themachine may be a personal computer (PC), a tablet PC, a set-top box(STB), a Personal Digital Assistant (PDA), a cellular telephone, a webappliance, a server, a network router, switch or bridge, or any machinecapable of executing a set of instructions (sequential or otherwise)that specify actions to be taken by that machine. Further, while only asingle machine is illustrated, the term “machine” shall also be taken toinclude any collection of machines (e.g., computers) that individuallyor jointly execute a set (or multiple sets) of instructions to performany one or more of the methodologies described herein.

The exemplary computer system 700 includes a processor 702, a mainmemory 704 (e.g., read-only memory (ROM), flash memory, dynamic randomaccess memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM(RDRAM), etc.), a static memory 706 (e.g., flash memory, static randomaccess memory (SRAM), etc.), and a secondary memory 718 (e.g., a datastorage device), which communicate with each other via a bus 730.

Processor 702 represents one or more general-purpose processing devicessuch as a microprocessor, central processing unit, or the like. Moreparticularly, the processor 702 may be a complex instruction setcomputing (CISC) microprocessor, reduced instruction set computing(RISC) microprocessor, very long instruction word (VLIW) microprocessor,processor implementing other instruction sets, or processorsimplementing a combination of instruction sets. Processor 702 may alsobe one or more special-purpose processing devices such as an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), a digital signal processor (DSP), network processor, or thelike. Processor 702 is configured to execute the processing logic 726for performing the operations described herein.

The computer system 700 may further include a network interface device708. The computer system 700 also may include a video display unit 710(e.g., a liquid crystal display (LCD), a light emitting diode display(LED), or a cathode ray tube (CRT)), an alphanumeric input device 712(e.g., a keyboard), a cursor control device 714 (e.g., a mouse), and asignal generation device 716 (e.g., a speaker).

The secondary memory 718 may include a machine-accessible storage medium(or more specifically a computer-readable storage medium) 731 on whichis stored one or more sets of instructions (e.g., software 722)embodying any one or more of the methodologies or functions describedherein. The software 722 may also reside, completely or at leastpartially, within the main memory 704 and/or within the processor 702during execution thereof by the computer system 700, the main memory 704and the processor 702 also constituting machine-readable storage media.The software 722 may further be transmitted or received over a network720 via the network interface device 708.

While the machine-accessible storage medium 731 is shown in an exemplaryembodiment to be a single medium, the term “machine-readable storagemedium” should be taken to include a single medium or multiple media(e.g., a centralized or distributed database, and/or associated cachesand servers) that store the one or more sets of instructions. The term“machine-readable storage medium” shall also be taken to include anymedium that is capable of storing or encoding a set of instructions forexecution by the machine and that cause the machine to perform any oneor more of the methodologies of the present invention. The term“machine-readable storage medium” shall accordingly be taken to include,but not be limited to, solid-state memories, and optical and magneticmedia.

In accordance with an embodiment of the present invention, amachine-accessible storage medium has instructions stored thereon whichcause a data processing system to perform an above described method ofdicing a semiconductor wafer having a plurality of integrated circuits.

Thus, methods of dicing semiconductor wafers, each wafer having aplurality of integrated circuits, have been disclosed. In accordancewith an embodiment of the present invention, a method includes applyinga protection tape to a wafer front side, the wafer having a dicing tapeattached to the wafer backside. The dicing tape is removed from thewafer backside to expose a die attach film disposed between the waferbackside and the dicing tape. Alternatively, if no die attach film isinitially disposed between the wafer backside and the dicing tape, a dieattach film is applied to the wafer backside at this operation. A watersoluble mask is applied to the wafer backside. A laser scribe isperformed on the wafer backside to cut through the die attach film andthe wafer, including all layers on the front side and backside of thewafer. A plasma etch is performed to treat or clean surfaces of thewafer exposed by the laser scribe. A wafer backside cleaning isperformed and a second dicing tape is applied to the wafer backside. Theprotection tape is the removed from the wafer front side. In oneembodiment, the wafer backside includes backside metallization anddielectric layers, and the wafer front side include device layers.

What is claimed is:
 1. A method of dicing a semiconductor wafercomprising a plurality of integrated circuits, the method comprising:applying a protection tape to a wafer front side, the wafer having adicing tape attached to the wafer backside; removing the dicing tapefrom the wafer backside to expose a die attach film disposed between thewafer backside and the dicing tape; and, subsequently, applying a maskto the wafer backside; and, subsequently, laser scribing from the waferbackside to cut through the mask, the die attach film and the wafer,including all layers within the front side and backside of the wafer;plasma etching to treat or clean surfaces of the wafer exposed by thelaser scribing; and, subsequently, cleaning the wafer backside andapplying a second dicing tape to the wafer backside; and, subsequently,removing the protection tape from the wafer front side.
 2. The method ofclaim 1, wherein applying the mask to the wafer backside comprisesapplying a water soluble mask to the wafer backside.
 3. The method ofclaim 1, wherein laser scribing from the wafer backside comprises usinga femtosecond-based laser scribing process.
 4. The method of claim 1,wherein laser scribing from the wafer backside comprises using apicosecond-based laser scribing process.
 5. The method of claim 1,wherein the wafer backside includes backside metallization anddielectric layers, and the wafer front side includes device layers. 6.The method of claim 1, wherein the wafer is a monocrystalline siliconsubstrate.
 7. The method of claim 2, wherein cleaning the wafer backsidecomprises removing the water soluble mask with an aqueous solution.
 8. Amethod of dicing a semiconductor wafer comprising a plurality ofintegrated circuits, the method comprising: applying a protection tapeto a wafer front side, the wafer having a dicing tape attached to thewafer backside; removing the dicing tape from the wafer backside; and,subsequently, applying a die attach film to the wafer backside; and,subsequently, applying a mask to the wafer backside; and, subsequently,laser scribing from the wafer backside to cut through the mask, the dieattach film and the wafer, including all layers included within thefront side and backside of the wafer; plasma etching to treat or cleansurfaces of the wafer exposed by the laser scribing; and, subsequently,cleaning the wafer backside and applying a second dicing tape to thewafer backside; and, subsequently, removing the protection tape from thewafer front side.
 9. The method of claim 8, wherein applying the mask tothe wafer backside comprises applying a water soluble mask to the waferbackside.
 10. The method of claim 8, wherein laser scribing from thewafer backside comprises using a femtosecond-based laser scribingprocess.
 11. The method of claim 8, wherein laser scribing from thewafer backside comprises using a picosecond-based laser scribingprocess.
 12. The method of claim 8, wherein the wafer backside includesbackside metallization and dielectric layers, and the wafer front sideinclude device layers.
 13. The method of claim 8, wherein the wafer is amonocrystalline silicon substrate.
 14. The method of claim 9, whereincleaning the wafer backside comprises removing the water soluble maskwith an aqueous solution.
 15. A method of dicing a semiconductor wafercomprising a plurality of integrated circuits covered by a protectiontape on a front side thereof and comprising metallization on a backsidethereof, the method comprising: exposing a die attach film disposed onthe semiconductor wafer backside; applying a mask to the exposed dieattach film on the semiconductor wafer backside; laser scribing from thesemiconductor wafer backside to cut through the mask, the die attachfilm, the metallization on the backside of the semiconductor wafer, thesemiconductor wafer, and the integrated circuits on the front side ofthe semiconductor wafer; plasma etching to treat or clean surfaces ofthe semiconductor wafer exposed by the laser scribing; and applying adicing tape to the laser scribed semiconductor wafer backside.
 16. Themethod of claim 15, wherein applying the mask to the semiconductor waferbackside comprises applying a water soluble mask to the semiconductorwafer backside.
 17. The method of claim 15, wherein laser scribing fromthe semiconductor wafer backside comprises using a femtosecond-basedlaser scribing process.
 18. The method of claim 15, wherein laserscribing from the semiconductor wafer backside comprises using apicosecond-based laser scribing process.
 19. The method of claim 15,wherein the wafer is a monocrystalline silicon substrate.
 20. The methodof claim 16, further comprising: subsequent to the laser scribing andprior to applying the second dicing tape, cleaning the semiconductorwafer backside by removing the water soluble mask with an aqueoussolution.